I suppose she is very scantily clad but then she's wearing about the same amount of clothing as the aeon Shiva - you just don't really notice it as much what with her blue skin and all. Frankly I was more bothered about how to kill her than what she was wearing though.

I only had issues with Yunalesca the very first time I played the game, it was my first RPG so I was new to how it all worked. I've never had an issue with her after that though, I've improved vastly since then.

As for Yuna, she dresses fine - it suits her, it's modest and fits her role as a summoner. If, however, you're referring to her outfit in X-2 then again I can't really say anything bad about it. It's just how she dresses really, it's a gunslinger outfit that's all. Essentially her outfits are practical for the role she's in within the respective game.

Auron's costume is fine, he's not meant to run around like tidus is because tidus needs that free flowing style of clothing to suit his battling style, auron uses 1 arm to fight so his clothing doesn't require much manuvourablity to perform the heavy hits